Healthy individuals from fALS families with a known genetic mutation will be included in this study. We encourage people who have previously undergone genetic testing and were found to carry the mutation that affects their family as well as those who do not know their genetic status to contact us. Those who wish to participate and to learn the results of genetic testing, may do so after undergoing genetic counseling. It is also possible to participate without learning the results of genetic testing. Participants eligible to complete study visits will travel to Miami (at our expense) approximately every 12-24 months for a period of 10 years or longer and will perform various biomarker procedures. Between visits, participants will complete phone calls about their health.